The diagenesis of amino acids in sediments from Clear Lake core CL-80-1 is indicated by changes in amino acid concentrations, compositions, and stereochemistry. Concentrations of total amino acids decrease with depth, but the decrease is not systematic, possibly reflecting a nonuniformity in sedimentary and postdepositional processes affecting the amino acids. Ratios of neutral/acidic amino acids may indicate that the pH of interstitial water is slightly alkaline to slightly acidic and that the organic matter is well humified. Ratios of nonprotein/protein amino acids suggest that some changes in amino acids with depth result from microbial degradations. The extent of racemization of alanine increases with depth; the trends of these data may be explained, in part, by rapid sedimentation within the lake. Agreement between extents of alanine racemization for sediments from equivalent depths in two cores from the lake suggests that diagenetic temperatures are uniform within the sediments of the northern basin of Clear Lake.

The geochemistry of amino acids in fossil wood materials appears to be applicable to geological problems such as correlation, relative-age dating, and paleothermometry of sedimentary deposits in the northern Yukon Territory, Canada (Rutter and Crawford, 1984). Activation energies and Arrhenius frequency factors were calculated for the racemization reaction of several bound amino acids (asp, ala, glu, leu). These parameters were obtained by determining elevated temperature rate constants for the bound amino acids isolated from modern and fossil Picea glauca (white spruce). The ratios of dextro to levro stereoisomers (D/L ratio) obtained for bound aspartic acid were found to be the most reliable and yielded values of 18.4 ±2.4 Kcal/mol and 27.6 ±3.0 yr −1 for activation energy and Arrhenius frequency factor ( ρ nA), respectively. Slight differences in kinetic parameters were obtained between fossil and modem wood replicates. Aspartic acid also yielded results correlatable to studies performed on Sequoiadendron giganteum (Engel and others, 1977). These findings suggested that species specific effects may not be significant for proteinaceous material found within wood matrices. Extrapolation of a first-order rate constant for bound aspartic acid in the fossil Picea sp. yielded a value of 9.75 × 10 −7 yr −1 . This constant was derived from the extent of racemization of the dated sample (>53,000 yr B.P.). Rate constants were similarly determined for various fossil localities in the northern Yukon. These rate constants ranged from 9.75 × 10 −7 yr −1 to 3.24 ± 0.2 × 10 −6 yr −1 . As this reaction is temperature dependent, estimations of paleotemperatures that the fossil samples had experienced were calculated. The values obtained (−49°C ± 30°C) were unrealistic since the racemization does not appear to follow simple reversible first-order kinetics. More reasonable results were obtained (−19°C) if the assumption used for calculation was based on the presence of free aspartic acid (complete protein hydrolysis). The apparent rate of racemization of free aspartic acid is characteristically lower than the apparent rates of racemization of protein-bound amino acids.

The aminostratigraphic relationships of approximately 150 coastal Quaternary sites from Nova Scotia to Florida and the Bahamas Islands are reviewed. The broad latitudinal range of the sites provides a useful perspective on the relative kinetics of racemization at substantially different temperatures. Local aminostratigraphic sections are presented for five regions in which present mean annual temperatures differ by 3°C or less. Correlation of these individual aminostratigraphies is accomplished by qualitative comparison of results for overlapping sections and by quantitative kinetic modeling. Correlations based on kinetic modeling with local calibration are compared with available U-series data for coastal plain sites. Using basic aminostratigraphic assumptions about the relationship of present and past temperature gradients, the amino acid data from most of the calibration sites follow logical trends. However, significant conflicts between U-series dates and aminostratigraphic age estimates are recognized for sites in South Carolina and for a group of sites in eastern Virginia (central Chesapeake Bay). Reconciliation of the aminostratigraphic data with all of the Atlantic Coastal Plain U-series coral dates is not possible without invoking extreme (and latitudinally variable) thermal effects on the racemization kinetics.